def is_palindrome(s):
    list_word=[]
    list_word_two=[]
    pan=1
    i=0
    l=0
    for word in s:
        list_word.append(word)
    for w in list_word[::-1]:
        list_word_two.append(w)
    while(pan!=0):
        if(list_word[i]!=list_word_two[i]):
            pan=0
            print("不是")
        else:
            i+=1
            l+=1
        if(l==len(list_word)):
            print("是")
            break
    print(list_word)
    print(list_word_two)
is_palindrome("ABAC")